1. Field of the Invention
The present invention relates in general to a liquid delivering apparatus. In particular, the present invention relates to, in such an apparatus which delivers liquid by giving pressure thereto owing to deformation of a piezoelectric element, an electric connection structure between an electrode for generating an electric field in the piezoelectric element and a drive circuit.
2. Discussion of Related Art
There is known a liquid delivering apparatus which delivers liquid accommodated in a liquid chamber to an exterior of the apparatus, by giving pressure to the liquid owing to deformation of a piezoelectric element. In such an apparatus, a drive voltage is supplied to an electrode for producing an electric filed in the piezoelectric element, so that the piezoelectric element is deformed to thereby give the pressure to the liquid in the liquid chamber. As one example of such a liquid delivering apparatus, JP-A-2002-240278 or its corresponding U.S. Pat. No. 6,595,628 discloses a piezoelectric-type ink jet recording head to be installed on an ink jet printer. The ink jet recording head disclosed in the Publication includes a cavity unit including a plurality of ink ejection nozzles from which ink is ejected and a plurality of pressure chambers corresponding to the respective nozzles, a piezoelectric actuator in which a plurality of internal electrodes provided for the respective pressure chambers and a plurality of piezoelectric sheets are arranged such that each internal electrode is interposed between adjacent two piezoelectric sheets, and a flexible flat cable on which a plurality of wires for supplying a drive voltage from a drive circuit to the internal electrodes are printed, the cavity unit, the piezoelectric actuator and the flexible flat cable being superposed on each other in this order.
On the uppermost surface of the piezoelectric actuator which is opposed to the flexible flat cable, there are formed surface electrodes which are connected to the wires of the flexible flat cable. The surface electrodes are connected, via an electrically conductive material filled in through-holes that are formed through the plurality of piezoelectric sheets in the direction of stacking thereof, to the respective internal electrodes which are aligned with the surface electrodes in the direction of stacking. The flexible flat cable is superposed or laminated on the uppermost surface of the piezoelectric actuator such that the surface electrodes are connected to the wires of the flexible flat cable, so that the drive circuit and the internal electrodes are electrically connected via the wires of the flexible flat cable. In the thus constructed ink jet recording head, when the drive voltage is applied from the drive circuit to the internal electrodes via the wires, the piezoelectric sheets interposed between the internal electrodes are deformed, whereby the ink in the pressure chambers are given the pressure, so that the ink is ejected from the nozzles.